An ultrasonic surgical system typically includes a generator, a transducer, cables, an ultrasonic surgical instrument, a foot switch or a hand switch, etc., here the ultrasonic surgical instrument further comprises a handle, a waveguide, and an end effector. When the ultrasonic surgical instrument is actuated by the foot switch or the hand switch, the generator outputs electrical power at a acoustic resonant frequency to the transducer, and the transducer converts the electrical power into mechanical energy that results in ultrasonic vibrations and transmits to the ultrasonic surgical instrument, which further amplifies the vibrations, so as to vaporize tissues, break down hydrogen bonds of proteins, make cells necrotic, and cut tissues or seal vessels, thereby functions of cutting tissue and hemostasis are achieved.
The ultrasonic surgical instrument is in threaded connection with the transducer. However, a stud of the transducer is so small that torque applied thereon may not beyond acceptance; otherwise the stud might be damaged, and further to damage the entire transducer.
The ultrasonic surgical instrument has to be replaced frequently and the ultrasonic surgical instrument should be assembled in reliable connection every time.
Commonly, the stud of the transducer is typically screwed using a wrench with a constant torque to thereby ensure the stud of the transducer to be connected reliably avoiding being damaged. The wrench is so small and dedicated that it is often lost in use, which makes the entire surgical instrument cannot work. Moreover the wrench is based on elastic deformation of plastic so as to generate a constant torque, but in use the torque varies due to manufacturing errors, material performance differences, and other factors, thus the torque may not be kept constant.
It is disclosed of prior art that a connective structure for connecting a transducer with an ultrasonic surgical instrument, including the transducer and the ultrasonic surgical instrument in threaded connection therewith. The transducer is provided with a stud, and the ultrasonic surgical instrument includes a housing, a waveguide and an end effector, both of which are arranged rotatably in the housing, wherein one end of the waveguide is in connection with the end effector, and the other end is in threaded connection with the transducer; and a protector is further arranged in the housing to make the waveguide rotate together with the stud when the torque reaches a certain threshold while the transducer is being screwed on tightly with respect to the waveguide. The protector includes a block ring, that is arranged in the housing and coaxial with the waveguide, and an elastic ring sleeved fixedly on the waveguide, here a block portion is arranged on an inner wall of the block ring, and an elastic piece portion is arranged on an outer wall of the elastic ring. During the transducer being tightly screwed with respect to the waveguide, when the torque is less than a predetermined value, the block portion is pushed against the elastic portion; when the torque is beyond the predetermined value, the elastic portion goes over the block portion and slip. In this arrangement, although the protector is arranged therein to limit the torque, and is not easy to lose, it may still face the same problem of reliability as the above mentioned wrench may have. Due to slip between the elastic ring and the block ring is caused by self-deformation of material of the block ring and the elastic ring, the torque provided by the protector may significantly vary due to manufacturing errors, material performance differences, material wearing in use, and other factors, thus it may have problems on reliabilities of connection between the transducer and the ultrasonic surgical instrument.